Domestic incinerator appliance



Dec. 12, 1967 s. K. WILEY, JR

DOMESTIC INCINERATOR APPLIANCE Filed Oct. 22. 1965 EXHAUST j COMPRESSEDAIR m ll IO 3 2 J. RU E P W P mw .IIIJ

CONTACTS INVENTOR Sumner K. Wiley, Jr.

ATTORNEY United States Patent 3,357,379 DOMESTIC INCINERATOR APPLIANCESumner K. Wiley, Jr., Hampton, N.H., assignor to Westinghouse ElectricCorporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct.22, 1965, Ser. No. 501,546 6 Claims. (Cl. 110-8) ABSTRACT OF THEDISCLOSURE An improved incinerator device of a type in which loosehousehold waste material is compacted into a plug that is presented to acombustion chamber for burning at a controlled rate, which improvementincludes temperature regulating means for maintaining temperature in thecombustion chamber above the allotropic transformation temperature oftin can material present in such waste, whereby tin cans are made morebrittle and their crumbling is facilitated during burning of the waste.

The object of the invention is to extend the utility of the small sizedhousehold incinerator by making it capable of disposing of tin cans,plastic containers, foil wrappings, and the usual household discardedtrash which is not by ordinary means quickly oxidizable. The disposal ofthis sort of trash is no problem in the large municipal incineratorswhere unburned trash is simply raked up and dumped, but in the smallsized device where a tin can may blanket a substantial portion of theburning face of the trash it becomes of importance because it should notbe allowed to interfere with the operation thereof. It is an object ofthe invention that the refuse be reduced to ash and not merely flattenedout metal. Accordingly, the mechanical structure of the tin cans must betransformed by a chemical process into a structure which may be reducedto an ash-like residue by conventional mechanical means in an acceptablyshort time.

The present invention resides fundamentally in a chemical process bywhich the household tin can may be trans formed structurally to abrittle and easily crumbled mass of ash. The material from which a tincan is fabricated may be oxidized, but by ordinary processes thisrequires such a long time that none of these ordinary processes may beused for. domestic waste disposers. Household incinerators have beendevised with crushing means incorporated therein whereby the discardedtin cans may be compacted for disposal in the ordinary. manner, but nomeans for reducing such material to ash or ash-like residue within thetime of operation of a domestic appliance has been provided.

According to the present invention, tin cans and similar objects arestuffed into the trash bin of a domestic incinerator where, in time,each will be subjected to a temperature above that at which allotropictransformation takes place whereupon these discarded bits of trashbecome brittle and easily comminuted so that the remains thereof passinto the ash receiver. By this means then, the household incinerator isrendered capable of disposing of all household waste.

Heretofore domestic incinerators have been constructed and arranged tooperate at a temperature of substantially 1500 F. which was foundsuflicient to reduce oxidizable material to a clear and odorless gas.However, throughout development of the disposers ability to destroy alltypes of waste, it was found that at these temperatures the commonhousehold tin can would merely form a protective tight-oxide coating onits outer surface, allowing a high percentage of metal to remain intact.Even after continuous exposure to an oxygen-rich atmosphere at 1500 F.,cans would not reach the fully oxidized, brittle state which "ice mightrender them susceptible to complete destruction by comminution. Theproblem was further aggravated by the fact that at these temperaturestin cans which had not completely oxidized and broken up would merelyflatten out in a softened, still metallic, condition and clog thecombustion chamber thereby choking off further combustion.

It has been discovered that by exposing tin cans to disposer combustionchamber atmosphere (corrosive), at temperatures above the transformationtemperature for hypoeutectoid steel, somewhere in the range of l600 to1800 F., the oxidation process is drastically accelerated to the pointwhere destruction of tin cans by incineration becomes practical. It hasbeen determined that the common household tin can, when subjected to a1900 F. combustion chamber atmosphere, will, in less than a half hour,reduce to a completely oxidized, brittle, flaking, fragile, distortedshape, which is totally susceptible to crumbling, crushing, orcomminution by others means.

Applicant believes that the reasons for the drastic change in oxidationrate which he has discovered are due to at least two facts. Firstly,there is greatly increased susceptibility to corrosion attack as aresult of complete allotropic transformation of low carbon ironcrystalline structure from body centered cubic to face centered cubic,i.e. alphairon to gammairon. When the transformation temperature isexceeded, a net shrinkage of metal results which, when simultaneouslybeing coated with ferric oxide of higher specific volume, results inrapid destruction of the protective oxide coating by cracking andflaking. Allotropic transformation also tends to produce a sensitizedmetal surface due to grain boundary precipitation. Secondly, there isincreased chemical reaction since chemical action in this temperaturerange approximately doubles for every 10 increase in temperature. Thesereasons for accelerated oxidation are based on commonly knowninformation concerning iron-carbon hypoeutectoid compositions andstudies concerning the inhibiting of corrosion and oxidation.

Unique to this disclosure, however, is a practical method foraccelerating the destruction of tin cans and other similar householdmetallic waste by intentionally permitting or causing active oxidationof this material to take place in a disposer operating at or above 1700F. This is the lowest temperature where allotropic transformation ofcommon tin can metal can be expected to be complete and oxidationbecomes rapid enough to make destruction of this type waste in adisposer practical from a time consideration.

In accordance with the present invention a combustion chamber isprovided in which a thin face layer of a compacted imporous mass ofhousehold trash may be ignited and consumed at a temperature ofsubstantially 1900 F. Oxygen rich air is heated in a firing chamber andplayed onto the face of the plug. A temperature probe reaches into thecombustion chamber and acts to control flow of combustion air or burningrate of the plug, and hence temperature. Close regulation of thetemperature at the burning face of the plug is important because thishigh temperature must be maintained in order to render the tin cansbrittle and easily converted to ash, but must not be allowed to reachmuch above this point due to materials limitations.

A feature of the invention is an incinerator device where the trash iscompacted into an imporous mass having a face comparable in size to apie tin, the botom face of which constitutes a wall of a combustionchamber and which is fired and maintained under combustion at a closelyregulated high temperature above the temperature of allotropictransformation of tin can metal.

Reference is made to patent application Ser. No. 329,- 044, filed Dec.9, 1963, by Malick, now Patent No.

3 3,313,253, which discloses certain features mentioned herein, whichapplication is incorporated herein and made a part hereof for thepurpose of a full explanation of the present invention.

Reference is also made to patent application Ser. No. 501,362, filed oneven date herewith in the name of Malick, which discloses a means forcontrolling the temperature of a combustion chamber in general at anypredetermined value and that disclosure should be incorporated herein asa part hereof.

Other features will appear hereinafter.

The drawings consist of a single sheet havinga single figure in the formof a schematic illustration partly in cross section of the elements ofan incinerator embodying the features of the present invention.

A combustion chamber 1 is constructed of a ceramic lining 2 in the lowerpart of an air tight container 3. Resting on the upper part of thisceramic lining 2 is a funnel shaped restriction ring 4. The upper partof the container 3 constitutes a trash bin into which trash 5, includingtin cans 6, 7 and 8, may be stuffed. A bellows like inflatable bag 9 isclamped by a cover 10 to the top of the trash bin 3 and may be inflatedfrom any convenient source of compressed air lL The pressure exerted bythe bag 9 as it becomes inflated compacts the trash into an imporousplug which is held back from any further downward movement by the funnelshaped restriction ring 4. The bottom face 12 of this plug of compactedmaterial thus forms one wall of the combustion chamber and it is thisface which is maintained under combustion. As a thin layer of this facebecomes eroded and shrunken, the prtssure exerted by the bag 9 causesthe plug to move forwardly keeping the carbonized and incandescentburning face substantially at the same place as burned material falls oris eroded away by other means. Where a tin can 6 has been moveddownwardly until part thereof protrudes from this bu-rning face, themetal thereof has, through the maintenance of a temperature in thecombustion chamber at a point slightly above the allotropictransformation value for tin can metal, becomes so brittle that onlysimple agitation is required for complete comminution.

Combustion of fact 12 is inducedby high temperature air flowing throughorifices 13, 14 and 15. The air comes from an air supply 16, which isthen switched by air valve 17 either. to duct 18 or duct 19. Duct 18leads to a firing chamber 20 which houses electrical resistance heater21 and which heats the air for delivery to the face 12 of the plugthrough the orifices 13, 14 and 15. The duct 19 delivers fresh air tothe combustion chamber but at a distance from the burning face 12.

A temperature probe 24 is inserted in the combustion chamber 1 and actsto switch the fresh air to duct 19 when the temperature rises beyond thepredetermined point to which it has been set or, alternatively, toswitch the fresh air to duct 18 when the temperature falls. The airvalve 17 may be operated by a solenoid 22.

An exhaust vent 23 is provided to strip the combustion chamber of thegaseous product of combustion.

What is claimed is:

1. An improvement in an incinerator device for reducing oxidizable wastematerial to a clear odorless gas with a minimum of large solid remainswhich includes:

means (2) defining a combustion chamber (1);

wastecompacting means (3, 4, 9, '10, 11) to compact trash which includestin cans (7, 8) into a plug (5) and to introduce such plug to saidcombustion chamt ber 1) for burning; and

air supply means (16) for said combustion chamber;

wherein the improvement comprises temperature regulating means (24, 22,17, 18, 19, 20, 13) including a temperature sensor (24) for maintainingtemperature in said combustion chamber (1) during burning of the plug(5) above the allotropic transformation temperature of the material ofsaid tin cans, whereby oxidation and brittleness of such cans isenhanced to facilitate crumbling.

2. The incinerator device of claim 1, wherein said temperatureregulating means maintains the combustion chamber temperature betweensubstantially 1600 F. and 1900 F.

3. The incinerator device of claim 1, further comprising electricheating means (21) under control by said temperature regulating meansfor raising combustion chamber temperature independently of plug-burningwhen required.

4. The incinerator device of claim 1, wherein said temperatureregulating means includes said air supply means (16).

5. The incinerator device of claim 3, wherein said temperatureregulating means includes said air supply means (16).

6. The incinerator device of claim 1, further comprising a verticaltrash bin (3) disposed above and opening downwardly into the top of saidcombustion chamber 1), and wherein said waste compacting means includesa movable abutment (9) disposed in said trashbin, and said plug of trashis imporous and exposed only at its bottom end to said combustionchamber.

References Cited UNITED STATES PATENTS JAMES W. WESTHAVER, PrimaryExaminer.

1. AN IMPROVEMENT IN AN INCINERATOR DEVICE FOR REDUCING OXIDIZABLE WASTEMATERIAL TO A CLEAR ODORLESS GAS WITH A MINIMUM OF LARGE SOLID REMAINSWHICH INCLUDES: MEANS (2) DEFINING A COMBUSTION CHAMBER (1); WASTECOMPACTING MEANS (3, 4, 10, 11) TO COMPACT TRASH WHICH INCLUDES TIN CANS(7,8) INTO A PLUG (5) AND TO INTRODUCE SUCH PLUG TO SAID COMBUSTIONCHAMBER (1) FOR BURNING; AND AIR SUPPLY MEANS (16) FOR SAID COMBUSTIONCHAMBER; WHEREIN THE IMPROVEMENT COMPRISES TEMPERATURE REGULATING MEANS(24, 22, 17, 18, 19, 20, 13) INCLUDING A TEMPERATURE SENSOR (24) FORMAINTAINING TEMPERATURE IN SAID COMBUSTION CHAMBER (1) DURING BURNING OFTHE PLUG (5) ABOVE THE ALLOTROPIC TRANSFORMATION TEMPERATURE OF THEMATERIAL OF SAID TIN CANS WHEREBY OXIDATION AND BRITTLENESS OF SUCH CANSIS ENHANCED TO FACILITATE CRUMBLING.